ABSTRACT
Objective:To evaluate our novel path based on anatomical division of the anterior lateral wall of calcaneus and the sustentaculum tali for precise sustentacular screw placement in the surgical treatment of calcaneal fractures of Sanders types Ⅱ and Ⅲ.Methods:The anterior lateral wall of the calcaneus was divided into the anterior-superior zone S 1, the anterior-inferior zone S 2, the posterior-superior zone S 3 and the posterior-inferior zone S 4 for demarcation of the screw insertion points by our method of Four Zones, and into the front, middle and rear sections by our method of Three Sections for demarcation of the screw target points. The specimens were scanned by CT and modeled by Mimics. On the 3D virtual model of the calcaneus, one screw was placed from each zone of the anterior lateral wall of the calcaneus to the sustentaculum tali body. The screw placement target for S 1 and S 2 was the medial intersection point P 1 of the front and middle sections of the sustentaculum tali, and that for S 3 and S 4 was the medial intersection point P 2 of the middle and rear sections of the sustentaculum tali. It was observed whether the screws were placed in the bone channel. A total of 72 patients were included who had been admitted to Department of Orthopaedics, Suqian Hospital Affiliated to Xuzhou Medical University for calcaneal fractures of Sanders types Ⅱ and Ⅲ from January 2017 to January 2021. They were divided into an anatomical division group and a 3D printing group according to their screw placement method for the sustentaculum tali. In the anatomical division group of 32 patients subjected to screw placement based on our anatomical division, there were 25 males and 7 females, aged from 24 to 60 years; in the 3D printing group of 40 patients subjected to screw placement assisted by 3D printing, there were 31 males and 9 females, aged from 25 to 58 years. The disparities between the parameters of sustentacular screw placement and the actual values were compared in the anatomical division group, and the total number of screws, screws on average, distribution of screws, and accuracy of screw placement were compared between the 2 groups. Results:All the screws which were virtually placed in the specimens of the calcaneus from S 1 and S 2 to P 1 and from S 3 and S 4 to P 2 passed through the bony channel, with no perforation into the tarsal sinus. There was no significant difference in the general date between the anatomical division group and the 3D printing group, showing they were comparable ( P > 0.05). In the anatomical division group, a total of 52 screws were placed to the sustentaculum tali with an average of (1.63 ± 0.48) screws per patient, and 2 screws were placed in 20 patients, yielding an accuracy rate of screw placement of 92.3% (48/52). There were no statistically significant differences between the parameters and the actual values of screw placement in the anatomical division group ( P > 0.05). In the 3D printing group, a total of 63 screws were placed to the sustentaculum tali with an average of (1.58 ± 0.49) screws per patient, and 2 screws were placed in 23 patients, yielding an accuracy rate of screw placement of 93.7% (59/63). There were no significant differences in the above comparisons between the anatomical division group and the 3D printing group ( P > 0.05). Conclusion:In the surgical treatment of calcaneal fractures of Sanders types Ⅱ and Ⅲ, the sustentacular screw placement based on our anatomical division of the anterior lateral wall of the calcaneus and the sustentaculum tali can lead to similar clinical accuracy as 3D printing-assisted screw placement does.
ABSTRACT
Objective:To evaluate the clinical application of virtual and simulation techniques to aid pre-operative design for precise screw placement into the sustentaculum tali in the treatment of intra-articular calcaneal fractures.Methods:From January 2016 to January 2019, 68 patients were treated at Department of Orthopaedics, Suqian Hospital Affiliated to Xuzhou Medical University for intra-articular calcaneal fractures of Sanders types Ⅱ-Ⅳ. According to different designs of screw placement into the sustentaculum tali, they were assigned into a control group (38 cases and 42 feet) and an observation group (30 cases and 33 feet). There were 24 males and 14 females with an age of 39.3 years±8.8 years in the control group. There were 17 males and 13 females with an age of 42.0 years ± 7.6 years in the observation group. The control group was given a routine placement design based on the X-ray and MSCT scanning images of the injured feet. In the observation group, a Mimics model was first constructed using the X-ray and MSCT scanning images of the normal or less injured feet for further virtual screw placement into the sustentaculum tali on a 3D printed model. The disparity was investigated between the parameters designed and the actual values in both groups. The 2 groups were compared in terms of average placements, screw distribution, placement accuracy, placement time and Maryland scores of foot function one year after operation.Results:There were no significant differences in the preoperative general data between the 2 groups, showing comparability ( P>0.05). The design parameters and actual values in the control group were respectively as follows: 17.7°±3.2° versus 15.1°±5.9° in upward oblique angle, 20.3°±2.1° versus 16.2°±6.8° in backward oblique angle, and 47.9 mm ± 3.8 mm versus 45.4 mm ± 4.2 mm in length of screw path, showing significant differences ( P< 0.05). The design parameters and actual values in the observation group were as follows: 16.5°±3.5° versus 17.1°±3.9° in upward oblique angle, 20.9°±4.3° and 19.6°±3.8° in backward oblique angle, and 48.1 mm ± 3.1 mm versus 47.3 mm ± 3.8 mm in length of screw path, showing insignificant differences ( P>0.05). The average screw placements into the sustenta culum tali in the observation group (1.6±0.5) were significantly more than those in the control group (1.2±0.4). Compared with the control group, the observation group had a higher rate of placement of 2 screws[60.6 % (20/23) versus 16.7% (7/42)], higher accuracy of placement [94.3% (50/53) versus 77.6% (38/49)], less placement time for each screw (9.6 mm±3.9 min versus 13.2 mm±4.7 mm), less placement time for each foot (15.6 mm±4.8 min versus 20.5 mm±3.8 mm), and higher Maryland scores at one year after operation (94.2±6.5 versus 89.7±6.9). All the above comparisons were statistically significant ( P<0.05). Conclusions:Application of virtual and simulation techniques to aid pre-operative design for precise screw placement into the sustentaculum tali can improve the outcomes of intra-articular calcaneal fractures, because it increases the number of screws placed, enhances quality of screw placement, shortens operation time, and thus facilitates functional recovery of the injured foot.